Mintaka (Delta Orionis)

Mintaka (Delta Orionis) is the seventh brightest star in the constellation Orion and the westernmost and faintest star in Orion's
Belt; its Arabic name means "the belt of the Central One." Mintaka is
a multiple star system, the main components of which are a hot (30,000 K) B star and an even hotter O
star, each with a mass of over 20 solar masses and a luminosity 70,000
times that of the Sun. These bright stars form a compact visual binary,
with a period of 5.73 days and a maximum separation of 0.3", and also an Algol star system showing a dip of about 0.2
magnitude during mid-partial eclipse. Two much dimmer and remote companions
trek around the central O-B couple. A magnitude 6.8 B star orbits at a distance
of about 0.25 light-year, while, closer in, circles a magnitude 14 component.

Mintaka is famous as a background against which the thin gas of interstellar
space was first detected, when the German astronomer Johannes Hartmann (1865-1936)
in 1904 discovered absorption in the
star's spectrum that could not be produced by the orbiting pair.